Simplify the following expression: $7\sqrt{208}$.
Solution: First, try to factor a perfect square out of the radical. $= 7\sqrt{208}$ $= 7\sqrt{16 \cdot 13}$ Separate the radical and simplify. $= 7\sqrt{16} \cdot \sqrt{13}$ $= 7 \cdot 4 \cdot \sqrt{13}$ $= 28\sqrt{13}$